2. Tragedy of the commons Rationale: “If I don’t use a free resource (air, fish, ducks) somebody else will. “The little bit I use or pollute will not matter” So with few users it is not a big problem, however; will an ever increasing human population, resources can be exhausted.

3. Sustainability Reliance on solar energy Biodiversity Population control Have your pet spade or neutered Nutrient recycling

4. The water cycle Where does new water come from? KEY TERMS FOR WATER CYCLE Precipitation Infiltration percolation runoff evaporation transpiration condensation

5. 2. What are some ways the water cycle is altered by human activities The withdrawing of large quantities of water from streams, lakes, and underground sources. Page. 314 Construction of roads increases runoff and soil erosion and slows down recharge of groundwater. Runoff of phosphates and nitrates into water.

7. Carbon cycle

8. 4. Excess carbon dioxide Burning of fossil fuels Removal of vegetation such slash and burn farming in the rain forest. Drive your vehicle at the recommended speed. Going above or below that speed will involve higher fuel consumption and higher pollution rate.

9. Nitrogen (N 2 ), a relatively inert gas, is the most abundant gas (78%) in the atmosphere. Nitrogen is an essential element for life, as it is needed in order to make important macromolecules such as amino acids, proteins and nucleic acids. Although the atmosphere has a large reservoir of nitrogen gas (78%), this nonreactive form is NOT readily available for use by living organisms. Therefore, nitrogen is often a limiting factor in ecosystems as its absence limits growth in primary producers at the base of the food chain (such as plants in terrestrial ecosystems and algae in aquatic ecosystems). Consequently, the nitrogen cycle is vital in that it converts nitrogen from the abundant unusable nitrogen gas found in the atmosphere to the nitrate and ammonium ions in the soil that can then be readily absorbed and utilized by primary producers (plants) in the ecosystem.

10. The Nitrogen Cycle

11. Fix NAAD ANPAN PROCESS PRODUCT Fix nitrogen fixation Ammonia Nitrification Nitrates Assimilation Proteins Ammonification Ammonia Denitrification Nitrogen

12. Remember Mutualism? Rhino and egrets

13. Carver developed techniques to improve soils depleted by repeated plantings of cotton. Together with other agricultural experts, he urged farmers to restore nitrogen to their soils by practicing systematic crop rotation: alternating cotton crops with plantings of sweet potatoes or legumes (such as peanuts, soybeans and cowpeas).cottonnitrogencrop rotation sweet potatoeslegumespeanuts soybeanscowpeas

14. Rhizobium bacteria and clover

15. Tuskegee Institute in Alabama

16. O by the way, the musical group the Commodores

17. 5. What are some human activities that effect the nitrogen cycle? We add NO nitrous oxide when burning fuel NO₃ can leach into the soil by using inorganic chemical fertilizers.

18. The Sulfur Cycle

19. Phosphorous Cycle note: There is form of phosphorous in the atmosphere.